1. Field of the Invention
The present invention relates to an imaging apparatus and a control method for the imaging apparatus and, more particularly, to a technique for dividing a video signal into a plurality of areas, and processing in parallel video signals in respective divided areas.
2. Description of the Related Art
In recent years, in imaging apparatuses including digital video cameras, a number of pixels which can be recorded has been increasing. The number of pixels which can be recorded by the imaging apparatus is also closely related to standards for monitors which display a video image recorded by the imaging apparatus. Specifically, the standards for monitors have shifted from a standard referred to as standard definition (SD) to a standard referred to as high definition (HD). The shift to the “standards for monitors” having a further higher resolution is scheduled in the coming years. The resolution of HD is mainly, horizontal 1920 pixels and vertical 1080 pixels (hereinafter, resolution is expressed as “(horizontal pixels)×(vertical pixels)” (expressed as “1920×1080” in this example)). The resolution of the “standard for monitor considered as the next generation” referred to as 4 k2 k is 3840×2160 pixels, which is a number of pixels four times as high as the HD. Further, a resolution of the standard planned in a digital cinema is 4096×2160 pixels, which is a higher number of pixels than 4 k2 k. Further, as the next generation further away than 4 k2 k, a standard referred to as 8k4k is also considered. The resolution of 8 k4 k is 7680×4320 pixels.
Along with such a change of the standards of monitors, high pixilation of images to be captured with respect to the number of pixels which can be recorded is required also in the imaging apparatus. For example, in order to be compatible with the monitor of 4 k2 k described above, the imaging apparatus needs to be provided with “a lens, an image sensor, a signal processing circuit for subjecting a video signal to digital processing, a video output large-scale integration (LSI) for outputting to the outside” and the like which are adapted to a high number of pixels. However, as the number of pixels gets higher, an information amount of a video signal output into one frame from an image sensor becomes larger. Accordingly, there are growing concerns about a problem that a signal processing circuit which performs digital processing becomes large-scaled. Japanese Patent Application Laid-Open No. 2003-006631 discusses a technique as a solution proposal of this problem. In the technique discussed in Japanese Patent Application Laid-Open No. 2003-006631, a plurality of signal processing circuits is provided. Then, the plurality of signal processing circuits processes the video signals in parallel. By doing so, speeding up and load distribution of a system are achieved.
Japanese Patent Application Laid-Open No. 2003-006631 discusses a technique in which an area of a video signal obtained by a high pixel sensor is divided into a plurality of sections. Then, image processing is performed in parallel by a plurality of signal processing circuits, on video signals of respective areas divided into a plurality of sections, and respective video signals which have been subjected to image processing are joined together. In the technique discussed in Japanese Patent Application Laid-Open No. 2003-006631, in a case where color-difference data to be used in white balance control, and luminance data to be used in exposure control are detected from a plurality of signal processing circuits, a resolution of areas where the color-difference data and the luminance data are detected become finer. Therefore, accuracies of the white balance control and the exposure control can be upgraded.
However, a microcomputer needs to acquire evaluation values of video images such as the color-difference data used for the white balance control, and the luminance data used for the exposure control, via communication media or the like from the plurality of signal processing circuits. As a result, there is a problem that it is not easy to speed up responsivity of the white balance control, and responsivity of the exposure control.
Further, in a case where the color-difference data and the luminance data used for the white balance and the exposure control are detected from an area across a part where a plurality of video signals is joined together, it is necessary to acquire these pieces of data from the plurality of signal processing circuits. For this reason, there is also a problem such that a communication system becomes complex, and it is necessary to calculate a plurality of evaluation values acquired from the plurality of signal processing circuits.